The present disclosure relates to a memory element capable of storing information in response to a change of electrical characteristics of a resistance change layer, to a drive method thereof, and to a memory device provided with this memory element.
In information equipment such as computer, as a random access memory, a high-density DRAM (Dynamic Random Access Memory) operating at a high speed has been widely used. As for the DRAM, however, the manufacturing process thereof is complicated compared with that of a general circuit used in electronic device, e.g., a logic circuit LSI (Large Scale Integrated circuit) and a signal processing circuit, and thus the manufacturing cost of the DRAM is high. Moreover, the DRAM is a volatile memory in which any written information is lost when the power is turned off, and there thus needs to perform a refresh operation frequently, i.e., an operation of reading any written information (data) therefrom, amplifying again the information, and writing again the information thereinto.
In consideration thereof, as a nonvolatile memory in which written information is not lost even if the power is turned off, previously proposed are flash memory, FeRAM (Ferroelectric Random Access Memory) (ferroelectric memory), MRAM (Magnetoresistive Random Access Memory) (magnetic memory element), and others. Such memories are capable of long-term storage of the written information without power supply. However, such memories each have advantages and disadvantages. That is, the flash memory is indeed high in degree of integration but is disadvantageous in terms of operation speed. The FeRAM has limitations in terms of microfabrication for a high integration degree, and has also a disadvantage of manufacturing process. The MRAM has a disadvantage of power consumption.
As such, as a next-generation nonvolatile memory, a memory element of a new type has been proposed, e.g., ReRAM (Resistive Random Access Memory) and PCM (Phase Change Memory) (for example, see Japanese Unexamined Patent Application Publication No. 2008-135659).